1. Field of the Invention
The present invention relates to a collapsible umbrella that can be folded into a flat shape. More specifically, the present invention relates to a collapsible umbrella that is effective when applied to three section umbrellas.
2. Description of the Related Art
FIG. 5 and FIGS. 6a to 6d show configuration examples of a conventional three section umbrella. As shown in FIG. 5, a collapsible umbrella of this type includes a cap 21′ fixed to the upper portion of a telescopic shaft 10′, collapsible ribs 40′ which are pivotally supported by the cap 21′, a slider 22′ which is slidably guided along the shaft 10′ below the cap 21′, and stretchers 44 which are pivotally supported by the slider 22′ and support the ribs 40′. When a canopy is opened, the ribs 40′ and the stretchers 44 are radially stretched and separated. Meanwhile, when the canopy is closed, the ribs 40′ are folded and are tied in a bundle with the stretchers 44, so that they are substantially in parallel with the shaft 10′.
The shaft 10′ is a telescopic shaft composed of a series of telescopic pipes. A ferrule 11 and a handhold 12 are attached to the front end (upper end) and the basal end (lower end) of the shaft 10′, respectively. Further, the shaft 10′ is provided with a latch 13 for releasably locking the slider 22′ at the intermediate portion near the front end (upper end) thereof.
Each of the ribs 40′ is formed of three foldable sections consisting of a top rib 41 (also referred to as long rib), an intermediate rib 42 and a tail rib 43. A supporting rib 45 (also referred to as back rod) is connected to each stretcher 44. Together with the top ribs 41 and the intermediate ribs 42, the supporting ribs 45 create a link mechanism by which the ribs 40′ are bent and stretched in conjunction with up-and-down movement of the slider 22′.
Wire springs 47 (also referred to as spring line) are provided to bridge between the top ribs 41 and the tail ribs 43. The intermediate portions of the wire springs 47 are locked to the intermediate portions of the intermediate ribs 42 so as to be movable, thus providing a spring action (spring function) to the ribs 40′ for bend and stretch movement.
The top ribs 41 and the intermediate ribs 42 are constructed from a metal member (e.g., steel or aluminum alloy) having a U-shaped cross section. As partially shown in FIG. 5 in closeup, the portion where the wire spring 47 is locked to the intermediate rib 42 so as to be movable is formed by bending an extending part 421, formed integrally with the intermediate rib 42.
Note that, in FIG. 5, reference numeral 51 denotes a protruding part or an extending part, each of which is referred to as a dowel and provided to form a joint that is rotationally movable.
FIGS. 6a and 6b respectively show the principal portions of the cap 21′ and the slider 22′. The cap 21′ and the slider 22′ are formed of cylindrical bosses having at their centers shaft guide holes 51a and 51b, respectively. The cap 21′ and the slider 22′ are respectively provided with longitudinal grooves 52a and 52b, which are pointing in directions radial to the shaft 10 at regular intervals (pointing in directions separated by 60° in the illustrative examples).
FIG. 6c shows the relative positions of a cap, a slider, ribs and stretchers of a conventional collapsible umbrella when a canopy is opened, and FIG. 6d shows the same when the canopy is closed. As shown in FIGS. 6c and 6d, the cap 21′ and the slider 22′ are provided with circular supporting wires (one turn wires) 54, going round the cap 21′ and the slider 22′ while passing through the longitudinal grooves 52a and 52b, respectively. The circular supporting wires 54 form a common spindle for pivotally supporting the top ribs 41 and the stretchers 44 to the longitudinal grooves 52a and 52b in a collective manner. Thus, as shown in FIG. 6c, the ribs 41 and the stretchers 44 are radially stretched and separated when the canopy is opened. Meanwhile, as shown in FIG. 6d, the top ribs 41 and the stretchers 44 are tied together in a bundle and are placed in a circle around the cap 21′ and the slider 22′ when the canopy is closed. In this case, although not shown, the three section ribs 40 are tied together in a bundle around the cap 21′ and the slider 22′, with the top ribs 41, the intermediate ribs 42 and the tail ribs 43 folded up.
The entirety or part of the above-described configuration of a collapsible umbrella is described, for example, in the following patent documents 1 to 5:
[Patent Document 1] Japanese Patent Laid-Open No. H09-51811
[Patent Document 2] Japanese Utility Model No. 3070862
[Patent Document 3] Japanese Patent Laid-Open No. H09-84617
[Patent Document 4] Japanese Patent Laid-Open No. H09-51811
[Patent Document 5] Japanese Patent Laid-Open No. H08-80207
As described previously, in a conventional collapsible umbrella, the ribs 40′ and the stretchers 44 are tied together in a bundle and are placed in a circle around the cap 21′ and the slider 22′ when the umbrella is folded up. In addition, the ribs 40′ are tied together in a bundle, with the top ribs 41, the intermediate ribs 42 and the tail ribs 44 folded up. Along with this, an umbrella canvas (not shown) is folded around the cap 21′ and the slider 22′ together with the ribs 40′.
For this reason, the umbrella has a cylindrical, thick, rounded shape when folded up as shown in FIG. 4b. When a collapsible umbrella having such a thick cylindrical shape is contained in a bag or the like, it may futilely create a thick spacing in the bag, cause an awkward bulging, and generate local compression on items in the bag. Furthermore, there has been inconvenience that such a collapsible umbrella cannot be contained in cases with a small thickness.
In this connection, the present inventor has focused on the fact that it is particularly effective to flatten the shape of a folded umbrella in order to increase convenience of housing and carrying of collapsible umbrellas, rather than miniaturizing the entire shape of a folded umbrella. The present inventor has also established that the miniaturization of the entire shape of a folded umbrella would entail reduction in the umbrella function, like reduction in the open size of an umbrella, which resulted in little improvement in the capability of housing of collapsible umbrellas in a bag or the like.
However, a collapsible umbrella having the conventional structure described above is folded in such a way that the ribs 40′ and the stretchers 44 are tied together in a bundle and are placed in a circle around the cap 21′ and the slider 22′. Accordingly, such a collapsible umbrella is forced to have a thick, cylindrical shape when folded up.